A source of light for indoor home and office environments is usually fluorescent light bulbs. The dominance of fluorescent lighting came about due to its superior efficiency and lifetime, compared to incandescent light bulbs. With advances in material science and nanotechnology, new light sources are being developed, which will exceed the efficiencies and longevity of fluorescent lights.
The spectral output of fluorescent lights does not cover the full visible light spectrum. Most of the light is in the red-orange region, with a few sharp peaks in the blue region. Because of this, the appearance of objects and people illuminated by fluorescent lighting differs considerably compared to the appearance of the same object and people illuminated by sunlight or incandescent light. Because lighting, and specifically the light spectrum, affects people's moods and influences the aesthetic perception of objects and people, better lighting technology is desirable. In addition, lighting is a major use of the world energy supply. A more efficient source of lighting provides energy savings and cost reduction.
The efficient generation of full spectrum white light is an important research topic because of the potential impact on the economies of lighting.
The most dominant form of lighting currently in use is fluorescent light, where an arc discharge of a gaseous mixture of Ar and Hg vapor produces UV light having a wavelength of about 420 nm, and where a phosphors coating the inside of a fluorescent tube convert the UV to visible light. A newer form of lighting takes advantage of light emitting diodes, and uses solid state materials in Groups III-V, such as InP, GaAs, etc., and where p-n doped junctions function as LEDs. LED light sources are generally more efficient, however, they produce only a single color of light, i.e., they generate light in a relatively narrow band of the visible light spectrum, and they are more expensive to manufacture than conventional incandescent or fluorescent lights. A general overview of solid state lighting as well as the direction of the technology is outlined in http://lighting.sandia.gov/lightingdocs/OIDA_SSL_LED_Roadmap_Full.pdf